Hawaiian Telcom says the cause of service outages on Tuesday was a fire believed to be intentionally set in the early morning hours beneath the H-1 Freeway airport viaduct which burned a large span of fiber optic cable.

"It was high, over the ledge and then back rolling up," said Honolulu Fire Capt. Terry Seelig.

Fire investigators said it started just after 1 a.m. on Tuesday in a trash-filled pocket under Nimitz Highway off Kilihau Street.

A homeless man was seriously burned. Investigators don't know if it was an accident or arson.

Homeless camps, and all the trash that goes along with it, has been a huge problem with the state for years.

Every six months, they say they literally clean out tons of stuff, but each time it builds up again.

But that problem led to a much bigger problem. Within minutes it triggered a massive ripple effect.

"Our Sprint radios went down totally as did our landlines," said Freeway Service Patrol Project Manager Mike Burgess.

"I quickly realized our service was down so I ran home grabbed my laptop," said Investment Banker Chris Pike of Wedbush Securities Inc. He said they were lucky the company has a backup private network they could rely on instead.

PHOTOS: Fire under H-1 viaduct

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A fire was reported underneath the H-1 Freeway airport viaduct near North Nimitz Highway and Kakoi Street Tuesday morning. You can see the smoke coming from the red portion of the picture.

"I tried to call the office real quick and couldn't get through," added Burgess. He said they clear roads and assist police with everything from rockslides to car crashes, but, on this day, HPD couldn't readily get a hold of them for any road incidents, until they figure out a way to channel their calls through the Department of Transportation.

Cable, cell and phone service stopped or was seriously hampered for large sections of West Oahu and Kauai, along with a still unknown number of customers statewide.

"It was a long stretch of fiber optic cable that was damaged pretty severely by the fire, so we'll have our crews out there to replace that section and there's painstaking splicing work that has to happen," said Simon.

The list kept growing on Tuesday. Oahu satellite city halls were affected. Most Kauai county offices, including police dispatch, were down.

Oceanic said it restored service to 15,000 customers Tuesday afternoon, but told its customers to expect slower service for several hours.

Hawaiian Telcom said 10,000 customers were hit, but KITV's newsroom had been getting calls and emails from areas supposedly not affected that afternoon.

Hawaiian Telcom had hoped to restore service to most of its customers by late Tuesday evening.